There are conventionally known navigation devices and systems for searching for a route from a desired departure location to a destination point and guiding a user with the aid of map data and road data. Such navigation devices and systems include car navigation devices mounted in automobiles so as to provide the driver with route guidance, navigation systems with a communication feature for sending a route search request to a route search server with the aid of a mobile phone as a navigation terminal and receiving the results and route guidance, as well as other devices and systems.
In particular, navigation systems with a communication feature are systems that use mobile phone or another mobile terminal as a navigation terminal, and are also used as navigation system for pedestrians. Pedestrian navigation systems preferably a route guidance function that includes transportation facilities, and there are navigation systems that, in addition to searching and providing walk route guidance, store route and operating time data of transportation facilities in a route search server, and also have a function for providing guidance along a route (boarding candidate trains) from a desired departure station to a desired destination point station, in addition to searching and providing guidance along a walking route. There are also transportation guidance systems for receiving and displaying routes, timetables, trains that can be boarded, and other information obtained from an information distribution server, and such information is unaccompanied by a route search for a walking route.
A navigation system for searching and providing guidance from a departure point to a destination point is disclosed in, e.g., Patent Reference 1 described below (Japanese Laid-open Patent Application No. 2001-165681) in which movement means constitutes walking, transportation facilities, and an automobile. The navigation system is configured so as to send departure point and destination point information from a mobile terminal device to an information distribution server, and search and provide guidance that matches the search conditions from road and transportation network data in the information distribution server. Examples of the search conditions include walking, automobile, the combined use of railroad and walking, and the like as movement means from the departure point to the destination point, and a route search is carried out using the above as one search condition.
The information distribution server is provided with a database in which the node points, curves, and other data of the roads (routes) in the map data are used as nodes, and also stores link data in which the routes connecting the nodes are used as links, and link cost data having cost information (distance and required time) of all the links. The information distribution server refers to a database, sequentially searches the links that start from the node of a departure point and end at the node of a destination point, and provides guidance by searching for the shortest route by following the nodes and links that minimize the cost information of the links and by using the result as a guidance route. A method referred to as the label determination method or the Dijkstra method is used as the route search technique. A route search method that uses the Dijkstra method is also disclosed in Patent Reference 1.
Also known are route search systems that search and provide guidance for a route from a departure point to a destination point using an airplane, train, trolley, bus, or other transportation means. Such systems are generally configured so as to refer to an operation timetable database, in which the operation timetable of transportation facilities have been organized in a database, on the basis of a user-specified departure time, departure point, destination point, arrival time, and other route search conditions, sequentially follow along routes that use transportation facilities that can be used to connect the departure point and the destination point including transfers, and presents one or a plurality of candidate guidance routes (trains and other transportation means) that match the route search conditions. In general, other route search conditions can also be specified, including required time, number of transfers, fares, and other conditions.
A guidance system is also provided as a search and guidance system related to transportation facilities in which a mobile phone or a terminal device can make a connection to an information distribution server that provides guidance in relation to route and timetable information of transportation facilities, receive information distribution of usable routes, trains, trolleys, and other transportation facilities when a desired departure station, departure time, a destination point station, and the like, and display the information on the terminal device. In the case that such use is made from a common terminal device, a configuration is used in which a URL (uniform resource identifier), domain name, or other address information for specifying the location of the desired download information is inputted to the terminal device, the information distribution server (information site) specified by the address is accessed, and the desired information is downloaded.
A railroad operates accurately in accordance with timetables as long as there has been no accident or vehicle breakdown, and the estimated time of arrival at a major station is suitably announced. The estimated time of arrival at a destination point is suitably announced in accordance with local weather conditions and airport conditions once the aircraft has taken off. In contrast, an express bus or a route bus that operates on ordinary roads is affected by road conditions and traffic congestion, and the time of arrival at a destination point is imprecise.
Even when there is an operation timetable, such is only an approximation. When a passenger has boarded a bus, there are no other choices and the estimated time of arrival cannot be predicted when the bus has entered congested traffic. The passenger often feels uncertainty in that the time of arrival at a destination point cannot be predicted in the particular case that the passenger is using a long-distance bus or an airport limousine bus and has a prescheduled appointment after arriving at a destination point.
In view of the above, attempts have been made to acquire positional information in real time from the buses actually operating along a route, and to provide guidance with good precision in relation to the estimated time of arrival at a bus stop. Such a system has been disclosed in, e.g., Patent Reference 2 (Japanese Laid-open Patent Application No. 2006-301735) and Patent Reference 3 (Japanese Laid-open Patent Application No. 2006-293443).
The bus-waiting time display system disclosed in Patent Reference 2 comprises bus passage time storage means for storing the time at which each bus has passed a bus stop; bus arrival time difference calculation means for calculating the bus arrival time difference between a next-arriving bus and an already-passed bus on the basis of the time difference between the time at which the next-arriving bus that will arrive next at a specified bus stop passes an immediately-preceding passed bus stop passed immediately prior to the specified bus stop and the time at which the already-passed bus that passed the specified bus stop has passed the immediately-preceding bus stop; and bus-waiting time display means for displaying the bus-waiting time obtained by subtracting the current time from the time obtained by adding the bus arrival time difference to the time at which the already-passed bus passed the specified bus stop.
The bus operation state display system disclosed in Patent Reference 3 comprises map information storage means for storing map information that includes bus stop information, operation state storage means for storing the operation state of a bus stopped at the bus stop, and map image creation means for displaying on an information display screen a map image for displaying a bus stop icon that displays the estimated time of arrival at which the bus will arrive at the bus stop.
Patent Reference 4 (Japanese Laid-open Patent Application No. 08-77494) discloses a traffic guidance device for providing route guidance that includes road congestion information, accident information, and other road-related traffic information. The traffic guidance system has an arrival time calculation section that calculates a plurality of times at which at buses on a bus line arrive at a departure point on the basis of: bus lines, scheduled operation time, and other information based on the timetable obtained from a bus timetable information storage section and departure point and destination point information inputted by the departure point/destination point input section; the current position information of buses obtained from the bus position information storage section; and congestion, accident, and other traffic information obtained from the traffic information storage section. Based on the calculated time, the route determination section is configured so as to determine an optimal bus line that will [allow the user] to arrive at a destination point in the shortest time, for example, and to display [the information] on a screen using a route display section 30.    [Patent Reference 1]: Japanese Laid-open Patent Application No. 2001-165681 (FIGS. 1 and 2)    [Patent Reference 2]: Japanese Laid-open Patent Application No. 2006-301735 (FIG. 11)    [Patent Reference 3]: Japanese Laid-open Patent Application No. 2006-293443 (FIGS. 2 and 3)    [Patent Reference 4]: Japanese Laid-open Patent Application No. 08-77494 (FIG. 1)